Egypt has said it will not use force to send back Palestinians who crossed from the Gaza Strip in large numbers after parts of the border were breached.

Foreign ministry spokesman Hossam Zaki said the border would be closed again when all the Palestinians had returned.

Tens of thousands have surged in to buy food and other supplies made scarce by an Israeli blockade - aimed at stopping rocket attacks from Gaza.

Israeli PM Ehud Olmert said he would not let a humanitarian crisis develop.

"We will not hit food supplies for children or medicines for the needy," he said.

"But there is no justification for demanding we allow residents of Gaza to live normal lives while shells and rockets are fired from their streets and courtyards at Sderot and other communities in the south."

Meanwhile about 15 Israeli tanks and armoured vehicles were seen in northern Gaza.

Israel confirmed that there had been "routine activity to stop terror" in the area.

A total of 350,000 Gazans crossed the Egyptian border, Israel's Haaretz newspaper reported. Hamas has not taken responsibility for breaching the border but quickly moved in to police it, the paper said, confiscating seven pistols from a man returning to Gaza.

Haaretz quoted one Gazan, Mohammed Abu Ghazel, as saying he had crossed the border three times with cigarettes which he had sold for five times the price he bought them.

"This can feed my family for a month," he said.

Talks offer

EGYPT-GAZA BORDER

12km (7.4 miles) long

Egyptian side patrolled by 750 soldiers under 2005 agreement with Israel

Border crossing terminal south of town of Rafah

PA control of terminal under EU supervision collapsed after Hamas takeover of Gaza in June 2007